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Rev. Notes > AS > Physical quantities and units
 
 
Previous Topic Physical quantities and units Next Topic

Topics
 

Physics

Areas of Physics

Interdisciplanary areas of physics

Quantities in Physics

Base Units

Convention for indicating units

Derived Units

S.I. Units (International System of Units)

Supplementary units

Homogeneity of equations

Significant figures

Rules of Significant figures

Further discussion on Significant figures

Dimensions

Scientific notation

The Avogadro's Constant

Scalars and Vectors

Addition and subtraction of co-planar vectors

Rectangular components of a vector

 

Quantities in Physics

The foundation of physics rests upon physical quantities in terms of which the laws of physics are expressed. Therefore, these quantities have to be measured accurately. Among these are mass, length, time velocity, force, density, temperature, electric current, and numerous others.
Physical quantities are often divided into two categories: base quantities and derived quantities.

Derived quantities are those whose definitions are based on other physical quantities. Velocity, acceleration and force etc. are usually viewed as derived quantities.

Base quantities are not defined in terms of other physical quantities. The base quantities are the minimum number of those physical quantities in terms of which other physical quantities can be defined. Typical examples of base quantities are length, mass and time.
The measurement of a base quantity involves two steps: first, the choice of a standard, and second, the establishment of a procedure for comparing the quantity to be measured with he standard so that a number and a unit are determined as the measure of that quantity.

An ideal standard has two principal characteristics: it is accessible and it is invariable. These two requirements are often incompatible and a compromise has to be made between them.

 

 
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  11/07/15 09:09 AM
   
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  26/01/15 07:00 PM
   
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  06/05/14 06:47 PM
 

 

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